Abstract

The production of a light Standard Model Higgs boson in association with a
top-quark pair at the Large Hadron Collider (LHC) is studied in a simulation of
the multipurpose ATLAS experiment. The Higgs boson is assumed to decay into a
b\bar{b} pair, and the top-quark pair to decay semi-leptonically. The main background
process for this channel is the production of t\bar{t} events, which can be divided into
reducible and irreducible components. In the process of generating these components
separately, an overlap of events is created through the addition of b-quarks to t\bar{t}
events via parton showering in the t\bar{t}X sample. These events are already included in
the matrix-element cross-section calculation for the t\bar{t}b\bar{b} sample. A new procedure
for the overlap removal is presented in this thesis.
Two analyses are studied, where one aims at the full reconstruction of the nal state
using a cut-based approach. Recently, this way of reconstructing the t\bar{t}H^{o}(H^{o}\rightarrow b\bar{b})
process has been found to be extremely challenging. The other analysis is based
on a new method employing state-of-the-art jet reconstruction and decomposition
techniques where the t\bar{t} pair and the Higgs boson are required to have large transverse
momenta and can therefore be reconstructed as massive Higgs and top jets. A
recent phenomenological study has shown that the t\bar{t}H^{o} process can be recovered
as a promising search channel for a low mass Standard Model Higgs boson around
120 GeV using this approach. Finally, to enhance the sensitivity of the t\bar{t}H^{o} channel,
a combination of the two analyses is presented.

Type:

Thesis
(Doctoral)

Title:

Investigation of the discovery potential
of a Higgs boson in the t\bar{t}H^{o}, H^{o} \rightarrow b\bar{b} channel with the ATLAS experiment

Open access status:

An open access version is available from UCL Discovery

Language:

English

Additional information:

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